Apparatus for separately controlling knitting means

ABSTRACT

Knitting means such as needles, sinkers, springs, raising cams, stitch cams and the like or their ferromagnetic portions are separately controlled in a knitting machine by an apparatus comprising a permanent magnet having two pole pieces extending therefrom. An adjustable magnetic shunt in the form of a stepped diameter adjusting screw bridges the pole pieces and is surrounded by an electrical coil. The coil is electrically coupled with the electronic control apparatus of the knitting machine. A spacing shim may be provided on one pole piece to produce and maintain a desired air gap between the pole pieces and the knitting means.

Hittite States Knourek et al.

atent 1 APPARATUS FOR SEPARATELY CONTROLLING KNITTING MEANS [75] Inventors: Jaroslav Knourek; Oldrich Kouril;

Vladimir Mureso, all of Brno, Czechoslovakia [73] Assignee: Vyzkumny a vyvojovg ustav Zavodu vseobecneho strojirenstvi, Brno, Czechoslovakia [22] Filed: Nov. 30, 1971 [21] Appl. No.: 203,204

[52] US. Cl. 66/154 A, 66/50 R [51] D04b 15/66 [58] Field of Search 66/50, 154 A; 336/ 136, 110

[56] References Cited UNITED STATES PATENTS 3,605,448 9/1971 Ribler 66/154 3,449,928 6/1969 Schmidt 66/134 X 3,518,845 7/1970 De Cerjat 66/50 3,262,285 7/1966 Beguiwetal 66/154 A X 3,262,079 7/1966 Glover et a1. 336/136 3,259,861 7/1966 Walker 336/136 3,254,319 5/1966 Olsen et al 336/136 2,494,579 l/l950 Pimlott et al. 336/136 3,390,364 6/1968 Russell 336/136 X 3,089,081 5/1963 Brosh 336/136 X Primary Examiner-Ronald Feldbaum Attorney-Arthur O. Klein [57] ABSTRACT Knitting means such as needles, sinkers, springs, raising cams, stitch cams and the like or their ferromagnetic portions are separately controlled in a knitting means.

3 Claims, 4 Drawing Figures 2/ Pd/r APPARATUS FOR SEPARATELY CONTROLLING KNITTING MEANS BACKGROUND OF THE INVENTION This invention relates to an apparatus for separately controlling knitting means such as, for example, needles, sinkers, springs, raising and stitch cams or the like, or their ferromagnetic portions, which means are used to produce patterns on knitting machines; and more particularly to apparatus for controlling said knitting means or their ferromagnetic portions by electrical and magnetic forces preferably acting through a permanent magnet having pole pieces and controlled by an electric coil.

The apparatus according to the present invention improves the operation of knitting machines which operate in a manner known to those skilled in the art from pattern data stored within an electrical control device. In accordance with the operational speed of these knitting machines, electrical current impulses are fed to electrical and magnetic control means causing them to change their magnetic state and thereby affect the positioning of a particular knitting means or, more particularly, its ferromagnetic portion. This principle of operation is shown, for example, in British Pat. Nos. 510,929 and 512,977 and in West German Pats. Nos. 745,181 and 581,892.

A more recent embodiment of an electromagnetic selection system employs a permanent magnet having pole pieces of soft iron, parts of which are surrounded by a coil. When this coil is excited, the permanent magnetic field of the coil-surrounded pole piece is weakened, reversed or counteracted, thus affecting the positioning of the ferromagnetic part of a kintting means such as a needle, sinker, spring, etc., which is to be controlled. More particularly the ferromagnetic part of the knitting meansdrops away from the faces of the pole pieces under the bias of an oppositely directed force, whereas it had previously been attracted to the pole pieces by means of the magnetic force of the permanent magnet.

A disadvantage of this recent system lies in the fact that any weakening of the magnetic field of the permanent magnet and its pole pieces enables the magnetic field of the coil to be completed through the permanent magnet. This may cause the permanent magnet to be de-magnetize or undergo an undesirable change in its attractive force. Where small springs of negligible diameter are used as knitting means in this system, the arrangement achieves a very high speed of operation. However, even a small amount of wear causes the spring stick diameter to decrease. This decreases the amount of magnetic flux which can be coupled through said stick, leading to a decrease in the effective attractive force of the permanent magnet.

Another known control system comprises a polarized electromagnet having an excitation winding located on a central pole piece, and with two windings each located on side pole pieces. The side pole pieces form a groove through which passes a ferromagnetic portion of a controlled knitting means, for example, a needle, sinker, spring, etc., A disadvantage of this system lies in the necessity of introducing polarized impulses into a coil winding. This makes the electronics of the knitting control means more complicated. Further difficulties are caused by the need to displace large masses by the' sole means of introducing energy into coils.

SUMMARY OF THE INVENTION The above-mentioned disadvantages are overcome by the present invention which provides an apparatus for separately controlling the knitting means or its ferromagnetic portion. The apparatus for controlling said knitting means employs a permanent magnet with pole pieces and an electric coil, said pole pieces being bridged by a suitably regulated shunt which forms an adjacent parallel branch of the magnetic circuit and which is surrounded by said electric coil. The regulated magnetic shunt is, according to the present invention, formed, for example, as a stepped diameter adjusting screw of magnetic material' The screw has a threaded portion which is screwed into a tapped hole in one of the pole pieces. The stepped diameter portion of the screw is in the form of a pin which is fitted in a receiving hole within the second pole piece.

At least one of the pole pieces is preferably provided with a spacing shim of hard material mounted to its outer side surface. The spacing shim extends beyond the plane of the front head portions of the pole pieces and through the air gap between said front head portions and the controlled ferromagnetic portion of the knitting means which may be a sinker.

One object of the present invention is to provide a system of apparatus in which each knitting stroke contains two points of selection in order to enable the selected movement of a controlled knitting means or its ferromagnetic portion movement into three different positions, for example, knit, tuck and miss. Each point of selection is controlled by means of a separate program from an electronic control system, said programs being fed into both selecting apparatus during each knitting stroke in unison and accurately synchronized.

Another object of the present invention is to provide an apparatus having a double selection during each knitting stroke to enable selected movement of, the controlled knitting means or its ferromagnetic portion into three different positions, for example, knit, tuck and miss, and wherein both points of selection are controlled by a single common program from an electronic control system. The program for the second selecting apparatus during a knitting stroke is delayed by 0.5 times the spacing of the synchronized impulses as compared with the program for the first selecting apparatus within the same knitting stroke.

The apparatus according to the present invention is advantageous in that it works with small energies since the magnetic flux excited in the coil is coupled primarily through the main parallel branch of the magnetic circuit, the magnetic resistance of which derives only from small air gaps between front head portions of the pole pieces and the controlled ferromagnetic portion of the knitting means. Further, the smaller portion of the magnetic flux is coupled through the permanent magnet in the direction of initial magnetization so that the value of said initial magnetization is continuously regenerated during the operation of the knitting machine. Accordingly the danger of de-magnetizing the permanent magnet is eliminated, whereas such de-magnetization is quite possible with prior art systems of electromagnetic selection which use permanent magnets.

If some failure should take place and a short-circuit current flows into the coil, the magnetic field formed by this short-circuit current will be directed in the direction of initial magnetization of the permanent magnet. Accordingly de-magnetization will not occur and cause a functional failure. The working parameters of the magnetic circuit containing the permanent magnet and the value of the necessary magnetomotive force of the coil can be adjusted by means of the stepped diameter screw such that the apparatus of the present invention meets required optimal functional parameters, even with the varying values of magnetization of the permanent magnet which normally occur during manufacture, and even with variations in the magnetic resistance of said circuit caused by dimensional or material differences.

BRIEF DESCRIPTION OF THE DRAWING To enable the nature of the invention to be more easily understood, one embodiment of the invention will now be described by way of an example with reference to the accompanying drawing, in which:

FIG. I is a sectional elevation of an apparatus for separately controlling knitting means according to the present invention.

FIG. 2 is a top plan view of the apparatus indicating the direction of movement of the controlled ferromagnetic portions of the knitting means, and their positioning with respect to the surfaces of the front head portions of the pole pieces.

FIG. 3 is a top plan view of said apparatus with different spacing between the first and second points of selection as compared with the points of selection shown in FIG. 2.

FIG. 4 is a schematic of the equivalent magnetic circuit for the apparatus according to the present invention, wherein:

Fm is the stationary source of magnetomotive force (permanent magnet),

Rm is the magnetic resistance of the source branch of the circuit,

Rmv is the magnetic resistance of the adjacent parallel branch of the circuit containing the adjustable magnetic shunt,

Rmh is the magnetic resistance of the main parallel branch of the circuit, that is the branch containing the controlled ferromagnetic portion of the knitting means,

Fe is the magnetomotive force of the shunt coil,

1pm is the magnetic flux of the permanent magnet,

rbml is the portion of the magnetic flux of the permanent magnet in the main parallel branch,

m2 is the portion of the magnetic flux of the permanent magnet in the adjacent parallel branch,

qbe is the magnetic flux excited by the coil in the adjacent parallel branch,

el is the magnetic flux of the coil which passes through the main parallel branch,

dJem is the portion of the magnetic flux excited by the coil which passes through the source branch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to the present invention, as it is shown in FIG. 1, comprises a permanent magnet 21 having pole pieces 22 and 23. Pole pieces 22 and 23 are bridged by an adjustable magnetic shunt consisting of an adjusting screw 24 having a threaded portion 24a which is screwed into the thread of a receiving hole 24b within pole piece 22. A non-threaded stepped diameter portion of screw 24 takes the form of a pin 31 and fits into a receiving hole 30 within the second pole piece 23. The magnetic shunt is surrounded by an electrical coil 25. Pole piece 23 is provided on its outer side surface 2321 with a spacing shim 26 of hard material, for example of sapphire, which may be fastened thereto by a screw 20. Shim 26 extends beyond the plane of the front head portions of pole peices 22 and 23 and through the air gap between the plane of said front head portions and the controlled ferromagnetic portion of the knitting means 27.

Referring to FIG. 2, a plan view of the apparatus according to the present invention indicates the direction of movement of the controlled ferromagnetic portions 27 of the knitting means (sinkers, needles, etc.) and shows how they are positioned adjacent the surface of the front head portions of pole pieces 22 and 23, for example, by means of a fixed camming member 32.

FIGS. 2 and 3 also show the so called cover pole pieces 28a, 28b and 280 which enclose the sides of each of the pole pieces 22 and 23 and their adjustable magnetic shunts 24. FIGS. 2 and 3 also illustrate two possible embodiments of cover pole pieces 28a, 28b and 280; for example, as shown in FIG. 2 they may be provided as an integral unit with pole pieces 23 and 22 and their magnetic shunts 24; alternately the cover pole pieces 28a, 28b and 28c may be provided as separate members which do not form an integral unit with pole pieces 22 and 23 and magnetic shunts 24, as shown in FIG. 3.

FIG. 2 also shows the spacing between the point of the first selection A and the point of the second selection B, said spacing may be expressed as:

where n is a whole number and t is the groove spacing. FIG. 3 indicates another manner of spacing the points of first and second selection A and B which may be expressed as:

where n is a whole number and t is the groove spacing.

The permanent magnet 20 can in one embodiment extend along the entire length of the selecting apparatus (for example, in the apparatus of FIG. 2); in another embodiment (see FIG. 3) each pair of pole pieces 22 and 23 may be provided with its own permanen magnet.

Each controlled ferromagnetic portion 27 when moved relative to the control apparatus in the direction S, is positioned adjacent the front surfaces of pole pieces 22 and 23 of permanent magnet 21 by interac tion with the beveled surface 32a of camming member 32. Once in position adjacent pole pieces 22 and 23, each ferromagnetic portion 27 is attracted by a mag netic force P At the same time the movement results in the application of an oppositely directed force P against each portion 27 whenever a resilient or cushioned controlled ferromagnetic portion 27 has been used. The force P acts to move the controlled ferromagnetic part 27 away from the front surface of the head portions of pole pieces 22 and 23 of permanent magnet 21. The magnetic force P,,, is set however so that it is greater than the force P and accordingly the controlled ferromagnetic portion 27 remains attracted to pole pieces 22 and 23.

Once the selection point A or B (see FIGS. 2 and 3) has been reached the controlled ferromagnetic portion 27 becomes a part of the magnetic circuit of permanent magnet 21 (also called herein the main parallel branch), through which passes a portion of the magnetic flux (bml of the permanent magnet dam. The value of the magnetic flux portion m1 is adjusted so that it exceeds by some security factor (for example, by 50 percent) a predetermined power condition. The magnetic flux within the main parallel branch may then be adjusted for operation by rotating the adjusting screw 24 which is located within the adjacent parallel branch of the magnetic circuit. Said adjusting screw 24, with its stepped diameter pin 31 fitted into the receiving hole in pole piece 23, acts to adjust the magnetic resistance of the adjacent parallel branch, and thus divides the total magnetic flux m between the adjacent and main parallel branches. If electric current is then fed into the coil 25 surrounding the adjacent parallel branch of the magnetic circuit, the magnetic flux (be is excited within said branch, said magnetic flux due being coupled through the main parallel branch where it acts through its component e1 against the initial magnetic flux m1 in this branch. The other portion dzem of the coil generated flux is dispersed or coupled through the source branch. The magnitude of the magnetomotive force Fe is selected so that the component of the magnetic flux d el within the main parallel branch will weaken or counteract the initial magnetic field m1 from permanent magnet Fm within the main parallel branch of the circuit. In other words the initial force P (FIGS. 2 and 3) is substantially decreased relative to the force P so that the controlled ferromagnetic portion 27 is, as a result of the now stronger directive force P pulled away from adjacent the surface of pole pieces 22 and 23. This is the way that the needle, for example, is moved into the knitting position for the next knitting stroke. If no impulse passes into coil 25 at selection point A, the ferromagnetic controlled portion 27 remains attracted to pole pieces 22 and 23 of permanent magnet 21, with the result that the needle remains set in the missing position.

The maintenance of an accurate air gap 8 between the controlled ferromagnetic portion 27 and the front head surfaces of pole pieces 22 and 23 is facilitated by the spacing shim 26 of hard material.

Predetermined points of selection can be arranged around the periphery of a knitting machine, or along its length in series. It is thus possible to obtain two or more points of selection in one knitting stroke. As is shown in FIGS. 2 and 3, points A are points for the first selection or knitting position of the needle and points B are points for the second selection or tucking position of the needle. lf selection is not carried out at either of those points of selection the needle passes into the third position, that is into the missing position of the needle.

We claim:

1. An apparatus for separately controlling knitting means such as needles, sinkers, springs, raising cams, stitch cams and the like or their ferromagnetic portions in response to electrical current impulses from the electronic control of a knitting machine, comprising, in

combination:

A. a permanent magnet having at least a pair of pole pieces magnetically coupled therewith,

B. an adjustable magnetic shunt bridging said pole pieces to form an adjacent parallel branch of the magnetic field of said permanent magnet,

C. an electrical coil surrounding said magnetic shunt and electrically coupled with said electronic control and D. a direct current source connected to the coil so that the magnetomotive force of the coil is in the same direction as the magnetomotive force of the permanent magnet.

2. An apparatus as defined in claim 1 wherein said adjustable magnetic shunt comprises a stepped diameter adjusting screw, a threaded portion of said screw being secured within a threaded receiving hole in one said pole piece, and the stepped diameter portion thereof forming a pin fitting into a receiving hole within the other said pole piece.

, 3. An apparatus as defined in claim 1 including a spacing shim mounted to a side surface of at least one said pole piece, said spacing shim extending beyond the plane of the front head portion of said pole piece by an amount sufficient to produce and maintain an air gap of predetermined width between said front head portions of said pole pieces and the controlled portion of a knitting means. 

1. An apparatus for separately controlling knitting means such as needles, sinkers, springs, raising cams, stitch cams and the like or their ferromagnetic portions in response to electrical current impulses from the electronic control of a knitting machine, comprising, in combination: A. a permanent magnet having at least a pair of pole pieces magnetically coupled therewith, B. an adjustable magnetic shunt bridging said pole pieces to form an adjacent parallel branch of the magnetic field of said permanent magnet, C. an electrical coil surrounding said magnetic shunt and electrically coupled with said electronic control and D. a direct current source connected to the coil so that the magnetomotive force of the coil is in the same direction as the magnetomotive force of the permanent magnet.
 2. An apparatus as defined in claim 1 wherein said adjustable magnetic shunt comprises a stepped diameter adjusting screw, a threaded portion of said screw being secured within a threaded receiving hole in one said pole piece, and the stepped diameter portion thereof forming a pin fitting into a receiving hole within the other said pole piece.
 3. An apparatus as defined in claim 1 including a spacing shim mounted to a side surface of at least one said pole piece, said spacing shim extending beyond the plane of the front head portion of said pole piece by an amount sufficient to produce and maintain an air gap of predetermined width between said front head portions of said pole pieces and the controlled portion of a knitting means. 